Side Release Buckle

ABSTRACT

A side release buckle includes: a plug; and a socket, the plug including: a base; a pair of legs; and engaging portions, the socket including: a body; an insertion opening; a housing space; engaged portions; and a pair of guide surfaces. The guide surfaces, which are formed on an inner surface of the housing space and extend in an insertion direction of the legs while being opposed to each other, each include: a squeezing portion formed continuously with corresponding one of the engaged portions; and a guiding portion formed between the squeezing portion and the insertion opening. An interval between the guiding portions near the engaged portions is wider than an interval between the squeezing portions near the engaged portions. An inclination angle of each guiding portion to an insertion direction of the plug is smaller than an inclination angle of each of the squeezing portion to the insertion direction.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/498,999 filed on Mar. 29, 2012 entitled “Side Release Buckle,” whichis a national stage application of PCT/JP2009/067042 filed on Sep. 30,2009, both of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a side release buckle that connects abelt and is provided with a pair of lock arms on both sides thereof.

BACKGROUND ART

There has been typically used a buckle that detachably engages a plugwith a socket in order to couple a string member such as a belt invarious applications such as clothes, bags, shoes and packages.

Such a buckle is required to be easily handled for coupling andreleasing and not to cause an accidental release when the buckle is notintended to be released. As a product responding to such needs, a siderelease buckle including a pair of lock arms on both sides thereof hasbeen used.

For instance, a side release buckle disclosed in Patent Literature 1includes a plug and a socket, each of which is provided with a beltattachment.

The plug includes a base including the belt attachment and a pair oflegs (lock arms) on both sides near the socket. The socket includes ahollow cylindrical body, which has a housing space (cavity) into whichthe plug is inserted through an insertion opening facing the plug.

Engaging portions formed at tip ends of the lock arms are engaged withengaged portions formed deep inside the housing space to maintain acoupling between the plug and the socket.

A pair of guide surfaces are formed on the inner surface of the housingspace (the inside of the top and bottom surfaces of the socket), andextend from the insertion opening to the engaged portions while beingopposed to each other so as to guide the engaging portions insertedthrough the insertion opening to the engaged portions.

The pair of guide surfaces, each of which is defined in a step on theinner surface of the socket, are linearly continuous from the insertionopening to the engaged portions. The pair of guide surfaces have aninterval in a tapered shape therebetween, the interval being wider nearthe insertion opening and narrower near the engaged portions.

When tip ends of the plug are inserted into the socket through theinsertion opening, the lock arms are smoothly guided into the housingspace by the pair of guide surfaces. Subsequently, when the plug ispressed deep inside, the pair of engaging portions formed at the tipends of the lock arms are squeezed in a direction to approach each otherby the pair of guide surfaces while being guided to smoothly fit in theengaged portions. In this manner, the engaging portions can be easilyand reliably engaged.

An opening in communication with the housing space is formed on eachside of the body of the socket. The engaging portions and the engagedportions can be disengaged by manipulating the legs exposed through theopenings by fingers.

In such a side release buckle, the plug and the socket each areintegrally formed mainly of a synthetic resin material. Accordingly,while the legs are provided with a predetermined elasticity, the plug,the socket and the belt attachment of each of the plug and the socketare provided with a sufficient strength to resist tension of the coupledbelt in use.

CITATION LIST Patent Literature

Patent Literature 1 JP-A-2009-11492

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the side release buckle disclosed in Patent Literature 1, when thelock arms of the plug are inserted into the socket, the pair of engagingportions are guided by the pair of guide surfaces while being squeezed,and then fit in the engaged portions. The guide surfaces disclosed inPatent Literature 1 define a continuous tapered shape from the insertionopening to the engaged portions. The guide surface on each side islinearly formed and is inclined at a predetermined inclination anglerelative to an insertion direction of the plug.

Immediately after the engaging portions, which are to be squeezed by theguide surfaces, are inserted through the insertion opening, the engagingportions contact with the guide surfaces to receive a squeezing force.The engaging portions are pressed against the guide surfaces by apredetermined contact pressure based on a reaction force of deformationof the lock arms. In other words, the engaging portions are rubbedagainst the guide surfaces over quite a long distance, during which asqueak noise is frequently generated.

In particular, when an interval between both sides of the engagedportions is sufficiently reduced as compared with an interval betweenthe engaging portions so as to improve the engaging performance, thesqueezing force of the guide surfaces needs to be increased. Thus, theguide surfaces are required to start squeezing the engaging portionsnear the insertion opening. In an arrangement in which the guidesurfaces start squeezing the engaging portions near the insertionopening, the engaging portions need to slide on the guide surfaces whilereceiving the squeezing force until reaching the engaged portions. As aresult, a squeak noise is more likely to be generated.

Further, a resistance to the engaging portions is increased during thesliding motion of the engaging portions on the guide surfaces, so thatthe insertion of the plug is likely to stop before engagement. When theengaging portions stop halfway on the guide surfaces as described above,the engaging portions are kept squeezed (not completely squeezed)halfway on the guide surfaces, and thus the lock arms are kept deformedfor a long time. Consequently, even when the plug is to be againcoupled, the plug is unlikely to be normally coupled because of adeformation tendency remaining in the lock arms.

An object of the invention is to provide a side release buckleconfigured to allow engaging portions to slide on guide surfaces lessforcefully while ensuring an appropriate guide function of the guidesurfaces.

Means for Solving the Problems

According to an aspect of the invention, a side release buckle includes:a plug; and a socket into which the plug is inserted for engagement, inwhich the plug includes: a base; a pair of legs that project from thebase; and engaging portions that are formed at tip ends of the legs andproject in a top-bottom direction, the socket includes: a body; aninsertion opening that is formed in the body and through which the legsare inserted; a housing space in which the legs inserted through theinsertion opening are housed; engaged portions that are engageable withthe engaging portions formed at the tip ends of the legs housed in thehousing space; and a pair of guide surfaces configured to guide theengaging portions inserted through the insertion opening to the engagedportions, the pair of guide surfaces are formed on an inner surface ofthe housing space and extend in an insertion direction of the legs whilebeing opposed to each other, the pair of guide surfaces each including:a squeezing portion being formed continuously with corresponding one ofthe engaged portions; and a guiding portion being formed between thesqueezing portion and the insertion opening, an interval between theguiding portions near the engaged portions is wider than an intervalbetween the squeezing portions near the engaged portions, and aninclination angle of each of the guiding portions relative to aninsertion direction of the plug is smaller than an inclination angle ofeach of the squeezing portions relative to the insertion direction ofthe plug.

In the above aspect, the pair of guide surfaces, each of which isgenerally defined in a step on the inner surface of the socket facingthe housing space, are opposed to each other. For instance, the stepsmay be provided by increasing the thickness of the body of the socket inthe vicinity of both sides thereof as compared with that in the vicinityof the central axis thereof. The side surfaces of the steps are usableas the guide surfaces. Alternatively, the steps may be provided byprotrusions formed on the inner surface of the socket. The side surfacesof the protrusions (steps) are usable as the guide surfaces. Althoughthe pair of guide surfaces are intended to be sufficiently wide to beresistant to the sliding motion of the engaging portions with contactpressure, each of the guide surfaces may have an appearance like a stripor a narrow rail such as a peripheral edge.

When each of the squeezing portions is provided by a linearly continuousstep, the inclination angle of the squeezing portion is defined by anangle between a continuing direction of the step and the insertiondirection of the plug. Likewise, when each of the guiding portions isprovided by a linearly continuous step, the inclination angle of theguiding portion is defined by an angle between a continuation directionof the step and the insertion direction of the plug. When each of thesqueezing portions is provided by a nonlinear step such as a curvedstep, the inclination angle of the squeezing portion may beapproximately defined by an angle between a straight line connectingboth ends of the squeezing portion and the insertion direction of theplug. Likewise, when each of the guiding portions is provided by anonlinear step such as a curved step, the inclination angle of theguiding portion may be approximately defined by an angle between astraight line connecting both ends of the guiding portion and theinsertion direction of the plug. The squeezing portions are required tobe inclined in such a manner as to be spaced from each other at anarrower interval near the engaged portions and at a wider interval nearthe guiding portions.

The interval between the squeezing portions near the engaged portions isrequired to be sufficiently narrow for the pair of engaging portions tobe squeezed to fit in the engaged portions. The interval between theguiding portions near the engaged portions may be wider than theinterval between the squeezing portions near the engaged portions sothat the guiding portions guide the engaging portions to the squeezingportions.

The engaged-portion sides of the guiding portions may be continuous withthe squeezing portions. In this case, the interval between the guidingportions near the engaged portions may be equal to the interval betweenthe squeezing portions near the insertion opening. The engaged-portionsides of the guiding portions may be discontinuous with the squeezingportions. As long as the engaged-portion sides of the guiding portionsare spaced at a narrower interval than the engaged-portion sides of thesqueezing portions, the engaging portions can be transferred to thesqueezing portions when the plug is inserted. In either case, it ispreferable that the minimum interval between the guiding portions is,for instance, wider than the interval between the pair of engagingportions with no load thereon so that the engaging portions receive nosqueezing force, or, alternatively, the minimum interval is an intervalfor the engaging portions to be slightly squeezed.

In the above aspect, when the legs of the plug are inserted through theinsertion opening of the socket and pressed in the insertion direction,the engaging portions at the tip ends of the legs are guided along theguide surfaces to fit in the engaged portions. Specifically, theengaging portions are guided deep inside the socket by the guidingportions, and then squeezed by the squeezing portions to fit in theengaged portions.

As compared with the squeezing portions, the guiding portions are spacedfrom each other at a wider interval over the entire length thereof, andare less inclined relative to the insertion direction, so that theguiding portions do not squeeze the engaging portions or may slightlysqueeze the engaging portions. Thus, while being guided by the guidingportions, the engaging portions can slide with less resistance. As aresult, it is possible to significantly lower a possibility of sufferingfrom a deformation tendency resulting from the halfway stopping andgenerating a squeak noise.

The squeezing portions have an inclination angle and an intervaldetermined such that the engaging portions having been guided by theguiding portions can be sufficiently squeezed to fit in the engagedportions. On the squeezing portions, the engaging portions may stophalfway, which may result in a deformation tendency, and generate asqueak noise. However, when the guiding portions having a large intervaltherebetween as a whole are formed over a part of a distance from theinsertion opening to the engaged portions, it is possible to lower apossibility of suffering from a deformation tendency resulting from thehalfway stopping and generating a squeak noise as a whole.

The sectional length of the squeezing portions is preferably, forinstance, at most one third of the distance from the insertion openingto the engaged portions. Such sectional distribution can reduce theratio of the sectional length of the squeezing portions to the distancefrom the insertion opening to the engaged portions. Thus, even thoughthe engaging portions inevitably stop halfway on the squeezing portions,it is possible to significantly lower a possibility of suffering from adeformation tendency resulting from the halfway stopping and generatinga squeak noise as a whole.

In the above aspect, the squeezing portions are formed over a shortsection with a steep inclination. Thus, when the plug is to be separatedfrom the socket, the popping action of the plug can be enhanced with theassistance of the elastic repulsion of the lock arms for an easierseparation.

Further, since the guide surfaces and the engaging portions provide aguiding function, it is not necessary to add any special guidingmechanism other than the legs to the plug, so that the weight and thecosts of the plug can be reduced.

In the above aspect, it is preferable that the interval between theguiding portions near the engaged portions is wider than an intervalbetween respective outermost sides of the engaging portions with no loadthereon.

With the above arrangement, when the pair of legs are inserted into thehousing space, the engaging portions at the tip ends of the legs are notsqueezed by the guiding portions. Even when the engaging portions slideon the guiding portions depending on the insertion state of the legs,the engaging portions are not squeezed. Thus, it is possible to lower apossibility of suffering from a deformation tendency resulting from thehalfway stopping and generating a squeak noise.

In the above aspect, it is preferable that the guide surfaces areparallel with each other along a direction of the guiding portions.

With the above arrangement, it is possible for the guiding portions toguide the engaging portions over a desired distance to the squeezingportions while keeping a constant relationship with the engagingportions. The guiding portions can thus increase the ratio of theguiding portions to the distance from the insertion opening to theengaged portions, so that it is possible to further lower a possibilityof suffering from a deformation tendency resulting from the halfwaystopping during insertion and generating a squeak noise.

In the above aspect, it is preferable that the guide surfaces eachfurther include an introducing portion in addition to the squeezingportion and the guiding portion, the introducing portion is continuouswith the insertion opening and the guiding portion, and an intervalbetween the introducing portions near the insertion opening is widerthan the interval between the guiding portions.

With the above arrangement, even when the interval between the guidingportions is smaller than the width of the insertion opening, the guidingportions and the insertion opening can be provided continuously witheach other for smooth insertion of the engaging portions or legs.

In the above aspect, it is preferable that the guiding portions and theintroducing portions are formed in conformity with an outer profile ofthe socket.

With the above arrangement, since the steps are formed in conformitywith the outer profile of the socket, the interval between the steps canbe maximized in the socket while the socket can have a thinner portionbetween the steps, which contributes to reducing the material and theweight of the socket.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a top surface of a buckle accordingto a first exemplary embodiment of the invention.

FIG. 2 is a perspective view showing a top surface of a plug accordingto the first exemplary embodiment.

FIG. 3 is a lateral side view showing the plug according to the firstexemplary embodiment.

FIG. 4 is a perspective view showing a top surface of a socket accordingto the first exemplary embodiment.

FIG. 5 is a front view showing an insertion opening of the socketaccording to the first exemplary embodiment.

FIG. 6 is a plan view showing the top surface of the socket according tothe first exemplary embodiment.

FIG. 7 is a plan view showing a bottom surface of the socket accordingto the first exemplary embodiment.

FIG. 8 is a sectional view showing guide surfaces according to the firstexemplary embodiment.

FIG. 9 is a sectional view showing guide surfaces according to a secondexemplary embodiment of the invention.

FIG. 10 is a sectional view showing guide surfaces according to a thirdexemplary embodiment of the invention.

FIG. 11 is a sectional view showing guide surfaces according to a fourthexemplary embodiment of the invention.

FIG. 12 is a sectional view showing guide surfaces according to a fifthexemplary embodiment of the invention.

FIG. 13 is a perspective view showing a top surface of a buckleaccording to a sixth exemplary embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the invention will be described below withreference to the attached drawings.

First Exemplary Embodiment

FIGS. 1 to 8 show a first exemplary embodiment of the invention.

As shown in FIGS. 1 to 3, a side release buckle 1 according to thisexemplary embodiment includes a plug 10 and a socket 20 into which theplug 10 is inserted for engagement.

As shown in the figures, the buckle 1 according to this exemplaryembodiment is used to couple and separate ends of a string member suchas a belt. The buckle 1 includes the plug 10 integrally formed of asynthetic resin and the socket 20 also integrally formed of a syntheticresin. The plug 10 and the socket 20 may be formed by other materialssuch as metal in addition to a synthetic resin by other forming methodsin addition to molding.

In FIGS. 1 and 2, an entirety of the plug 10 is integrally formed of asynthetic resin by molding. The plug 10 includes a base 11 having a beltattachment 19 and a pair of legs 12, and an engaging portion 14 formedin each of the legs 12.

The legs 12 extend in a length direction of the base 11 (an insertiondirection of the plug 10 to the socket 20, i.e., in a vertical directionin FIG. 1) from both sides of the base 11 in a width direction (adirection orthogonal to the insertion direction of the plug 10 to thesocket 20 and a top-bottom direction of the socket 20, i.e., ahorizontal direction in FIG. 1). The legs 12 are parallel with eachother. Portions from the centers to the tip ends of the legs 12 areelastically deformable in a direction separating from each other or in adirection approaching each other (the above-described width direction).

The pair of legs 12 are gradually inclined in the direction approachingeach other toward the tip ends of the legs 12 in the insertion directionand are curved with a predetermined clearance, so that the legs 12 canreceive elastic deformation force as a whole.

The engaging portion 14 is formed as a projection extending from the tipend of each of the legs 12 in a vertical direction (the top-bottomdirection of the socket 20). The tip end of each of the legs 12 isT-shaped in a lateral side view. In other words, the engaging portion 14is formed at the tip end of each of the legs 12. A dimension in atop-bottom direction (height) of the engaging portion 14 is set largerthan a height of each of the legs 12.

The belt attachment 19 is formed in a middle area of the base 11.

As shown in FIG. 2, the belt attachment 19 includes a string attachmenthole 19A as a string attachment portion into a center of which an end ofthe string member is inserted for engagement, and a connecting bar 19Bbridging over the string attachment portion in the middle thereof. Theconnecting bar 19B divides the string attachment hole 19A into a fronthole 19C in the insertion direction and a rear hole 19D in the insertiondirection. With this arrangement, a length of the string member can beadjusted by inserting the string member through the string attachmenthole 19A and winding the string member around the connecting bar 19B.

In FIG. 2, the tip ends of the pair of legs 12 are connected by aU-shaped connecting portion 15.

Both sides of the connecting portion 15 extend from the engagingportions 14 of the tip ends of the legs 12 toward the belt attachmentportion 19, respectively, and approach each other to be connected in aU-shape. With this connecting portion 15, the pair of legs 12 can beprevented from being excessively pulled outward by an external force. Apair of guided portions 16 are provided between the pair of legs 12.

As shown in FIG. 3, each of the guided portions 16 has the same heightas that of the engaging portion 14 of the tip end of each of the legs12. An upper periphery of each of the guided portions 16 projects upwardbeyond an upper periphery of each of the legs 12 while a lower peripheryof each of the guided portions 16 projects downward beyond a lowerperiphery of each of the legs 12.

The engaging portions 14 and the guided portions 16 are guided by guidesurfaces 30 and undulations 26(both described later) formed in a centralportion of the socket 20 so that the plug 10 is guided to an appropriateposition in an insertion operation.

As shown in FIG. 2, the guided portions 16 are connected to each othervia a connecting frame 16A near the base 11. The connecting frame 16Aconnects opposing portions of the guided portions 16 near the base 11. Amiddle portion of the connecting frame 16A is curved in a manner toproject in the insertion direction of the plug 10. A height of themiddle portion of the connecting frame 16A in a top-bottom direction isset lower than a height of each of the guided portions 16. The height ofthe middle portion is increased toward ends of the connecting frame 16Aand reaches the height of each of the guided portions 16 at the ends ofthe connecting frame 16A. Thus, top and bottom surfaces of theconnecting frame 16A are gradually dented at respective centers thereof.This profile corresponds to the outline of a convex 26B formed on aninner surface of a body 21 (described later).

In FIGS. 1 and 4, an entirety of the socket 20 is integrally formed of asynthetic resin by molding. The socket 20 includes: the hollowcylindrical body 21 including a belt attachment 29 and an insertionopening 22; a housing space 23 being formed in the body 21 and capableof housing the legs 12 of the plug 10 to be inserted through theinsertion opening 22; and an engaged portion 24 being formed in the body21 and engageable with the engaging portion 14. In order to release theengagement of the engaging portions 14 and the engaged portions 24, amanipulation opening 27 is formed on the body 21. The manipulationopening 27 is formed on each of lateral sides of the body 21 andcommunicates with the housing space 23 inside the body 21.

As shown in FIG. 4, the engaged portion 24 is provided as stepsrespectively formed at four positions inside the housing space 23 andfacing the belt attachment 29 (in a direction opposite to the insertionopening 22). Two of the four step-shaped engaged portions 24 are formedon an inner side of the bottom surface of the body 21 and face thehousing space 23 and side portions 29A of the belt attachment 29 of thebody 21. The other two of the four steps, which are formed on an innerside of the top surface of the body 21 in the same manner as the above,are covered by projections 25A on the top surface of the body 21. Theengaged portion 24 is provided by a pair of steps among the four steps,the pair of steps respectively formed on the top and bottom surfaces andfacing each other. In the socket 20 according to this exemplaryembodiment, the engaged portions 24 lining in a width direction are madein a pair and correspond to the engaging portions 14 formed in the pairof legs 12.

As shown in FIGS. 1 and 4, the manipulation opening 27 is positioned toexpose a middle portion of each of the legs 12 inserted through theinsertion opening 22. By pressing inward the legs 12 exposed out of themanipulation openings 27, the pair of legs 12 are elastically deformedto approach each other and the engaging portions 14 are released fromthe engaged portions 24, so that the mutual engagement is released.

As shown in FIGS. 4 and 5, a pair of guide surfaces 30 are formed in thehousing space 23 to guide the engaging portions 14 to the engagedportions 24 for engagement.

The guide surfaces 30 are defined in steps formed continuously from thevicinity of both ends of the insertion opening 22 to the engagedportions 24 along the top and bottom surfaces of the body 21. When thelegs 12 are inserted through the insertion opening 22, the guidesurfaces 30 serve as a guiding mechanism for guiding the engagingportions 14 formed at the tip ends of the legs 20 to the engagedportions 24. In other words, the engaging portions 14, which are locatedat the tip ends of the legs 12 inserted through the insertion opening22, are guided by the guide surfaces 30 and are squeezed to approacheach other due to the elastic deformation of the pair of legs 12. Whenthe engaging portions 14 reach the engaged portions 24, the legs 12elastically deformed by the guide surfaces 30 are recovered, so that theengaging portions 14 fit in the engaged portions 24 for mutualengagement.

As shown in FIG. 8, the pair of guide surfaces 30 are formedcontinuously from the engaged portions 24 to the vicinity of theinsertion opening 22, and each include a squeezing portion 31, a guidingportion 32 and an introducing portion 33.

The squeezing portion 31 of each of the guide surfaces 30 is formed overa section Si adjacent to the engaged portion 24 of the guide surface 30,and is linearly formed as a whole in a direction D1 intersecting with aninsertion direction D0 of the plug 10 at an inclination angle A1. Theinclination angle A1 is determined such that the squeezing portion 31 isinclined to deform the legs 12 and to squeeze the pair of engagingportions 14 when the plug 10 is inserted into the housing space 23through the insertion opening 22.

Ends of such a pair of squeezing portions 31, which are adjacent to theengaged portions 24, are opposed to each other at an interval W1. Theinterval W1 is sufficiently narrower than the interval between the pairof engaging portions 14 of the plug 10 when no load is applied to theplug 10, and falls within a range such that the legs 12 are deformed andthe pair of engaging portions 14 are squeezed. Thus, when the plug 10 isinserted into the housing space 23 through the insertion opening 22, thepair of engaging portions 14 are squeezed due to the inclination of thesqueezing portions 31. When reaching the engaged portions 24, theengaging portions 14 are released from the squeezing, and are againseparated from each other to fit in the pair of engaged portions 24.

The guiding portion 32 of each of the guide surfaces 30 is formed over asection S2 adjacent to the squeezing portion 31 of the guide surface 30,and is linearly formed as a whole in a direction D2 being parallel withthe insertion direction D0 of the plug 10 (i.e., an inclination angleA2=0). Thus, such an opposed pair of guiding portions 32 are parallelwith each other and are spaced from each other at an interval W2. Aconnecting portion between the guiding portion 32 and the squeezingportion 31 of each of the guide surfaces 30 is formed in an arc smoothlycontinuous with the guiding portion 32 and the squeezing portion 31 sothat the engaging portions 14 can smoothly slide irrespective of thedifference between the inclination angle A2 and the inclination angleA1.

The introducing portion 33 of each of the guide surfaces 30 is formedover a section S3 adjacent to the guiding portion 32 of the guidesurface 30. The introducing portion 33 is smoothly continuous with theguiding portion 32 and is formed in an arc so that the interval betweenthe introducing portions 33 of the pair of guide surfaces 30 reaches themaximum width of the insertion opening 22.

Since each of the introducing portions 33 is formed in an arc, adirection D3 of the introducing portion 33 cannot be simply determined.Accordingly, the direction D3 may be approximately defined by adirection of a straight line connecting an end of the introducingportion 33 near the guiding portion 32 and an end of the introducingportion 33 near the insertion opening 22.

The direction D3 of the introducing portion 33 intersects with theinsertion direction D0 of the plug 10 at an inclination angle A3. Theinclination angle A3 is larger than the inclination angle A1 of thesqueezing portion 31 because the introducing portion 33 is intended notto squeeze the engaging portion 14 but to guide the engaging portion 14to the guiding portion 32.

The outermost sides of the pair of engaging portions 14 are spaced fromeach other at an interval W0, which is larger than the interval W2between the guiding portions 32. Thus, when the introducing portions 33lead the pair of engaging portions 14 to the guiding portions 32, thepair of engaging portions 14 are squeezed by the introducing portions33. Although the introducing portions 33 are each curved in an arc andhave the large inclination angle A3 as a whole, the introducing portions33 can squeeze the pair of engaging portions 14 because the introducingportions 33 have a small inclination angle in the vicinity of the endsthereof continuing with the guiding portions 32. In this manner, thepair of engaging portions 14 are introduced to the guiding portions 32while being slightly squeezed. The pair of engaging portions 14 slide onthe guiding portions 32 with a slight contact pressure to be guided tothe squeezing portions 31.

The body 21 includes an undulation 26 continuously formed in aninsertion direction of the legs 12 substantially at a center of each ofthe top and bottom surfaces of the body 21.

As shown in FIG. 5, the undulation 26 is provided by a concave 26Aformed on an outer surface of the body 21 and a convex 26B formed on aninner surface of the body 21 along the concave 26A. A thickness of aportion defined by the concave 26A and the convex 26B is the same asthose of other portions of the body 21. In other words, the body 21 iscross-sectionally a corrugated plate provided by curving a portion of aflat plate.

The undulation 26 is formed on each of the top and bottom surfaces ofthe body 21, so that the body 21 is formed like a corrugated platecurved in a direction in which the centers of the top and bottomsurfaces facing each other approach. This arrangement can securestrength substantially at the centers where press force working in thetop-bottom direction is most likely to be applied and cracks are likelyto generate, and is effective for preventing crush and cracks.

The undulations 26 are positioned on the top and bottom surfaces of thebody 21 to correspond to each other. The convexes 26B of the undulations26 are positioned to fit in respective dents on the top and bottomsurfaces of the connecting frame 16A between the legs 12 inserted intothe housing space 23. A gap between the convexes 26B is set smaller thanthe height of each of the engaging portions 14 and the height of each ofthe guided portions 16 (the dimension in the top-bottom direction). Whenthe legs 12 are inserted, the engaging portions 14 and the guidedportions 16 are guided along the undulation 26. The undulation 26provides a guiding function to suitably guide the engaging portions 14to the engaged portions 24 while adjusting a posture of the plug 10. Atthis time, since being provided with the dents on the top and bottomsurfaces, the connecting frame 16A between the guided portions 16 can beinserted into the gap of the convexes 26B without interference with theconvexes 26B.

A height of the housing space 23 into which each of the guided portions16 is introduced is set equal to the height of the guided portion 16.While the guided portions 16 remain inserted in the housing space 23,when the socket 20 is pressed in the top-bottom direction, the guidedportions 16 support the socket 20 and prevent excessive deformation suchas crush in the top-bottom direction.

As shown in FIGS. 6 and 7, on each of the top and bottom surfaces of thebody 21, a cutout 28 extending along the undulation 26 is provided byforming the center of a widthwise edge of the insertion opening 22 in anarc dented toward the belt attachment 29 and a cutout 25 extending alongthe undulation 26 is provided by forming the center of a widthwise edgeof a belt-insertion opening near the belt attachment 29 in an arc dentedtoward the insertion opening 22.

The cutout 25 is a deep U-shaped cutout extending from the beltattachment 29. The cutout 28 is a shallow C-shaped cutout extending fromthe insertion opening 22. The most inward parts of the cutouts 25 and 28are shaped in an arc.

The outline of a C-shaped edge of the cutout 28 is set equal to theinner shape of the connecting frame 16A formed in the base 11 of theplug 10. With this outline, while the cutout 28 is maximally enlarged,the base 11 is not exposed more than necessary.

The outline of a U-shaped edge of the cutout 25 is set equal to theouter profile of the legs 12 and the connecting portion 15. As describedabove, the tip ends of the pair of legs 12 are connected to each otherby the connecting portion 15, the inside of which is in a U-shape as awhole. The outline of the cutout 25 is formed in line with this shape.With this outline, while the cutout 25 is maximally enlarged, the legs12 and the connecting portion 15 are not exposed.

In the cutout 25 formed on the top surface of the body 21 among thecutouts 25, portions facing both edges of the belt attachment portion 29are provided as projections 25A projecting along the belt attachment 19.The above-described engaged portions 24 near the top surface are coveredby the projections 25A. The projections 25A prevent the belt inserted inthe belt attachment 29 from being improperly lifted up.

The cutout 25 formed on the bottom surface of the body 21 includes noportion corresponding to the projections 25A. A part of an edge of thecutout 25 is formed along the step of each of the engaged portions 24,so that the engaged portions 24 are exposed from the bottom surface ofthe body 21.

As shown in FIG. 4, a height of the side portions 29A of the beltattachment 29 of the body 21 is larger than that of a belt-windingportion of the belt attachment 29, so that a sufficient connectionstrength is attained.

In this exemplary embodiment, when the legs 12 of the plug 10 areinserted through the insertion opening 22 of the socket 20 and arepushed in the insertion direction D0, the engaging portions 14 formed atthe tip ends of the legs 12 are guided by the guide surfaces 30 to fitin the engaged portions 24. Specifically, the engaging portions 14 areinitially guided to the guiding portions 32 by the introducing portions33 while being slightly squeezed. When the plug 10 is further pushed,the engaging portions 14 are guided along the guiding portions 32 to beinserted further inside the socket 20. The engaging portions 14 are thensufficiently squeezed by the squeezing portions 31 to fit in the engagedportions 24.

The guiding portions 32, which are parallel with each other at theinterval W2, are spaced from each other wider than the squeezingportions 31 as a whole. Further, the inclination angle A2 of each of theguiding portions 32 relative to the insertion direction D0 is constantlyequal to 0. Thus, the engaging portions 14 are not so strongly squeezedby the guiding portions 32 as by the squeezing portions 31. Assumably,even though the engaging portions 14 are guided to the guiding portions32 while being slightly squeezed by the introducing portions 33, theengaging portions 14 can slide with a slight resistance. Thus, whilebeing guided by the guiding portions 32, the engaging portions 14 canslide with less resistance. Thus, it is possible to significantly lowera possibility of suffering from a deformation tendency resulting fromthe halfway stopping of the engaging portions 14 and generating a squeaknoise.

The inclination angle A1 and the interval W1 of the squeezing portions31 are determined such that the engaging portions 14 having been guidedby the guiding portions 32 can be sufficiently squeezed to fit in theengaged portions 24. On the squeezing portions 31, the engaging portions14 may stop halfway, which results in a deformation tendency, and maygenerate a squeak noise. However, since the introducing portions 33 andguiding portions 32 occupy a large part of the distance from theinsertion opening 22 to the engaged portions 24 to reduce a partcorresponding to the squeezing portions 31, it is possible to lower apossibility of suffering from a deformation tendency resulting from thehalfway stopping of the engaging portions 14 and generating a squeaknoise as a whole.

In particular, in this exemplary embodiment, the section Si for thesqueezing portions is, for instance, at most one third as long as thedistance from the insertion opening 22 to the engaged portions 24. Suchsectional distribution can reduce the ratio of the squeezing portions 31to the distance from the insertion opening 22 to the engaged portions24. Thus, even though the engaging portions 14 inevitably stop halfwayon the squeezing portions 31, it is possible to significantly lower apossibility of suffering from a deformation tendency resulting from thehalfway stopping and generating a squeak noise as a whole.

The introducing portion 33 and the guiding portion 32 of each of theguide surfaces 30 are partly formed in an arc along the manipulationopening 27 of the socket 20. Thus, since it is not necessary to providean extra thickness to the body 21 of the socket 20, a material can beefficiently usable.

In this exemplary embodiment, since the undulations 26 are formed in theinsertion direction of the legs 12, the undulations 26 are allowed tohave no interference with an insertion operation of the legs 12 and tohave a guiding function for the engaging portions 14 of the legs 12 andthe guided portions 16.

Further, since the undulations 26 are interposed between portions forhousing the legs 12 in the housing space 23 in a projecting manner, whenthe pair of legs 12 are inserted into the housing space 23, the legs 12enter both sides of the undulations 26, so that a thickness (a dimensionin the top-bottom directions of the buckle) of each of the legs 12 andthe undulations 26 can be increased without mutual interference betweenthe legs 12 and the undulations 26 for effectively ensuring strength.

Moreover, the undulations 26 also serve as a guide to guide the engagingportions 14 to the engaged portions 24 when the legs 12 are insertedtherein, so that the plug 10 and the socket 20 can be easily andreliably engaged with each other.

Second Exemplary Embodiment

FIG. 9 shows a second exemplary embodiment of the invention.

A side release buckle 2 according to this exemplary embodiment includesthe same plug 10 and socket 20 as those in the first exemplaryembodiment. It should be noted that this exemplary embodiment isdifferent from the first exemplary embodiment in the sectionaldistribution for the guide surfaces 30 in the socket 20.

In this exemplary embodiment, as shown in FIG. 9, the section S2 for theguiding portions 32 is increased while the section S3 for theintroducing portions 33 is correspondingly reduced.

The introducing portions 33 are each formed in an arc and have theinclination angle A3 in the same manner as in the first exemplaryembodiment, but the interval W3 is considerably reduced.

The pair of guiding portions 32 are parallel with each other and thedirection D2 thereof is equal to the insertion direction D0 (i.e., theinclination angle A2 is equal to 0) in the same manner as in the firstexemplary embodiment.

The section S1, the direction D1 and the inclination angle A1 of thesqueezing portions 31 are not changed.

This exemplary embodiment also provides the same advantages as those ofthe first exemplary embodiment. Further, since the section for theguiding portions 32 is increased, the attitude of the plug 10 relativeto the socket 20 can be stabilized at an earlier phase to facilitate theinsertion of the engaging portions 14. It should be noted that since theinterval W3 is considerably reduced, in order to introduce the pair ofengaging portions 14 to the guiding portions 32, it is necessary to, forinstance, seek for the guiding portion 32 within the range of theinterval W3.

Third Exemplary Embodiment

FIG. 10 shows a third exemplary embodiment of the invention.

A side release buckle 3 according to this exemplary embodiment includesthe same plug 10 and socket 20 as those in the first exemplaryembodiment. It should be noted that this exemplary embodiment isdifferent from the first exemplary embodiment in the respective shapesand arrangements of the introducing portions 33 and the guiding portions32.

While the introducing portions 33 according to the first exemplaryembodiment are each formed in an arc, the introducing portions 33according to this exemplary embodiment are linearly formed. Further,according to this exemplary embodiment, the introducing portions 33 eachhave an end located on the edge of the insertion opening 22, andlinearly extend into the housing space 23 along the direction D3intersecting with the insertion direction D0 at the inclination angle A3to be continuous with the guiding portions 32.

While the guiding portions 32 according to the first exemplaryembodiment are parallel with each other, the pair of guiding portions 32according to this exemplary embodiment linearly extend along thedirection D2 intersecting with the insertion direction D0 at theinclination angle A2 to define a slightly tapered shape.

In this exemplary embodiment, since the section for the guiding portions32 is increased, the attitude of the plug 10 relative to the socket 20can be stabilized at an earlier phase to facilitate the insertion of theengaging portions 14.

This exemplary embodiment also provides the same advantages as those ofthe first exemplary embodiment.

Fourth Exemplary Embodiment

FIG. 11 shows a fourth exemplary embodiment of the invention.

A side release buckle 4 according to this exemplary embodiment includesthe same plug 10 and socket 20 as those in the first exemplaryembodiment. It should be noted that this exemplary embodiment isdifferent from the first exemplary embodiment in the respective shapesand arrangements of the introducing portions 33 and the guiding portions32.

Although the introducing portions 33 according to the first exemplaryembodiment are each formed in an arc, the introducing portions 33according to this exemplary embodiment are linearly formed. Further,according to this exemplary embodiment, the introducing portions 33 eachhave an end located on the edge of the insertion opening 22, andlinearly extend into the housing space 23 along the direction D3intersecting with the insertion direction D0 at the insertion angle A3to be continuous with the guiding portions 32. The above features arethe same as those in the third exemplary embodiment.

While the guiding portions 32 according to the first exemplaryembodiment are parallel with each other and linearly extend, the guidingportions 32 according to this exemplary embodiment are each formed in anarc and have the inclination angle A2 relative to the insertiondirection D0. Since each of the guiding portions 32 is formed in an arc,the direction D2 may be approximately defined by a direction of astraight line connecting an end of the guiding portion 32 near theintroducing portion 33 and an end of the guiding portion 32 near thesqueezing portion 31.

Further, according to this exemplary embodiment, each of the guidingportions 32 is not continuous with the squeezing portion 31.Specifically, the ends of the guiding portions 32 near the squeezingportions 31 are opposed to each other at the interval W2, which issmaller than an interval between ends of the squeezing portions 31 nearthe guiding portions 32. Each of the guiding portions 32 and thefollowing squeezing portion 31 is coupled to each other in a crankshape, so that the sliding motion of the engaging portions 14 from theguiding portion 32 to the squeezing portion 31 is easily acceptable, butthe inverse motion is restrained by the crank-like portion.

This exemplary embodiment also provides the same advantages as those ofthe first exemplary embodiment. Further, even when the engaging portions14 come out of the engaged portions 24, the crank-like portions betweenthe guiding portions 32 and the squeezing portions 31 serve to restrainthe engaging portions 14, so that an accidental separation of the plug10 can be reliably prevented.

Fifth Exemplary Embodiment

FIG. 12 shows a fifth exemplary embodiment of the invention.

A side release buckle 5 according to this exemplary embodiment includesthe plug 10, the socket 20 and the guide surfaces 30 as in the firstexemplary embodiment. It should be noted that the plug 10 and the socket20 according to this exemplary embodiment are different from those ofthe first exemplary embodiment in the outline of the body 21, the shapeof the legs 12, or the like.

According to this exemplary embodiment, the guide surfaces 30 eachinclude linear portions, i.e., the introducing portion 33, the guidingportion 32 and the squeezing portion 31. The introducing portions 33 areformed over the section S3, the direction thereof is D3, the inclinationangle thereof is A3, and the interval therebetween is W3. The guidingportions 32 are formed over the section S2, the direction thereof is D2(which is equal to the insertion direction D0 and thus the guidingportions 32 are parallel with each other), the inclination angle thereofis A2 (which is equal to zero), and the interval therebetween is W2. Thedirection of the squeezing portions 31 is D1, the inclination anglethereof is A1, and the interval therebetween is W1. Such an arrangementis the same as that of the first exemplary embodiment except that eachof the introducing portions 33 is not in an arc.

This exemplary embodiment also provides the same advantages as those ofthe first exemplary embodiment.

Second Exemplary Embodiment

FIG. 13 shows a sixth exemplary embodiment of the invention.

A side release buckle 6 according to this exemplary embodiment includesthe plug 10, the socket 20 and the guide surfaces 30 as in the firstexemplary embodiment. According to this exemplary embodiment, neitherthe cutout 25 nor 28 as shown in the first exemplary embodiment (seeFIG. 1) is formed and a longer undulation 26 is continuously formed fromthe edge of the insertion opening 22 to the belt attachment 29.

According to this exemplary embodiment, since the cutouts 25 and 28 inFIG. 1 are not provided, the material and the weight of the body 21 areless reduced. However, except for this, the same advantages as those ofthe first exemplary embodiment can be obtained. Further, the longerundulation 26 according to this exemplary embodiment can enhance therigidity of the body 21 as compared with the undulation 26 according tothe first exemplary embodiment.

Modifications

It should be noted that the invention is not limited to the abovearrangements of the exemplary embodiments but encompasses the followingmodifications.

The distribution ratio of the squeezing portion 31, the guiding portion32 and the introducing portion 33 in each of the guide surfaces 30 maybe altered as needed. Each of the squeezing portion 31, the guidingportion 32 and the introducing portion 33 may be linearly formed orformed in an arc, and the direction, the inclination angle and theinterval thereof may be appropriately determined depending on thefunction thereof.

Although the introducing portion 33 is formed in each of the aboveexemplary embodiment, the formation of the introducing portion 33 may beomitted. For instance, in the second exemplary embodiment shown in FIG.9, although the introducing portion 33 is formed in each of the guidesurfaces 30 over a narrow section, i.e., the section S3, the formationof the introducing portion 33 may be omitted. Alternatively, the guidingsection 32 may be elongated to keep the ratio of the squeezing portion31 small, thereby achieving the advantages of the invention.

Although each of the guide surfaces 30 is defined in a step in the aboveexemplary embodiments, the guide surface may be provided by a sidesurface of a protrusion formed on the inner surface of the socket 20. Inother words, the invention only requires that a pair of opposing guidesurfaces are formed to guide the pair of engaging portions 14 in such amanner that the engaging portions 14 are gradually squeezed as beingcloser to the engaged portions 24.

INDUSTRIAL APPLICABILITY

The invention is usable as a side release buckle that connects a beltand is provided with a pair of lock arms on both sides thereof.

EXPLANATION OF CODES

-   1, 2, 3, 4, 5, 6 side release buckle-   10 plug-   11 base-   12 leg(s)-   14 engaging portion(s)-   20 socket-   21 body-   22 insertion opening-   23 housing space-   24 engaged portion(s)-   27 manipulation opening(s)-   30 guide surface(s)-   31 squeezing portion(s)-   32 guiding portion(s)-   33 introducing portion(s)-   A1 an inclination angle of the squeezing portion(s) relative to an    insertion direction-   A2 an inclination angle of the guiding portion(s) relative to the    insertion direction-   A3 an inclination angle of the introducing portion(s) relative to    the insertion direction-   D1 an insertion direction-   D1 a direction of the squeezing portion(s)-   D2 a direction of the guiding portion(s) D3 a direction of the    introducing portion(s)-   S1 a section for the squeezing portion(s)-   S2 a section for the guiding portion(s)-   S3 a section for the introducing portion(s)-   W0 a distance between the outermost sides of the engaging portions    with no load thereon-   W1 an interval between the squeezing portions near the engaged    portions-   W2 an interval between the guiding portions near the engaged    portions-   W3 an interval between the introducing portions near the insertion    opening

1. A side release buckle comprising: a plug; and a socket into which theplug is inserted for engagement, wherein the plug comprises: a base; apair of legs that project from the base; and engaging portions that areformed at tip ends of the legs and project in a top-bottom direction,the socket comprises: a body; an insertion opening that is formed in thebody and through which the legs are inserted; a housing space in whichthe legs inserted through the insertion opening are housed; engagedportions that are engageable with the engaging portions formed at thetip ends of the legs housed in the housing space; and a pair of guidesurfaces configured to guide the engaging portions inserted through theinsertion opening to the engaged portions, the pair of guide surfacesare formed on an inner surface of the housing space and extend in aninsertion direction of the legs while being opposed to each other, thepair of guide surfaces each comprising: a squeezing portion being formedcontinuously with corresponding one of the engaged portions; and aguiding portion being formed between the squeezing portion and theinsertion opening, an interval between the guiding portions near theengaged portions is wider than an interval between the squeezingportions near the engaged portions, and an inclination angle of each ofthe guiding portions relative to an insertion direction of the plug issmaller than an inclination angle of each of the squeezing portionsrelative to the insertion direction of the plug.
 2. The side releasebuckle according to claim 1, wherein the guide surfaces are parallelwith each other along a direction of the guiding portions.
 3. The siderelease buckle according to claim 1, wherein the guide surfaces eachfurther comprise an introducing portion in addition to the squeezingportion and the guiding portion, the introducing portion is continuouswith the insertion opening and the guiding portion, and an intervalbetween the introducing portions near the insertion opening is widerthan the interval between the guiding portions.
 4. The side releasebuckle according to claim 3, wherein the guiding portions and theintroducing portions are formed in conformity with an outer profile ofthe socket.
 5. The side release buckle according to claim 1, wherein theinterval between the guiding portions near the engaged portions is widerthan an interval between respective outermost sides of the engagingportions with no load thereon.
 6. A side release buckle comprising: (a)a plug, comprising: (i) a plug belt attachment and (ii) a pair of legs,each leg including at least one socket engaging portion; (b) a socket,comprising: (i) a socket belt attachment, (ii) a housing spaceconfigured to receive at least portions of the pair of legs, (iii) atleast two plug engaging portions configured to engage the at least onesocket engaging portion of each leg when the plug is inserted into thesocket along an insertion direction, and (iv) at least a pair of guidesurfaces extending along an inner surface of the housing space andconfigured to interact with the socket engaging portions of the plug ina sliding fashion, wherein the guide surfaces each include at least aguiding portion and a squeezing portion, the squeezing portion locatedbetween the guiding portion and one of the plug engaging portions,wherein an approximate inclination angle of the squeezing portionrelative to the insertion direction is greater than an approximateinclination angle of the guiding portion relative to the insertiondirection.
 7. The side release buckle of claim 6, wherein a length ofthe guiding portion along the insertion direction is longer than alength of the squeezing portion along the insertion direction.
 8. Theside release buckle of claim 6, wherein the guide surfaces each alsoinclude an introducing portion located between the guiding portion andan insertion opening of the socket.
 9. The side release buckle of claim8, wherein an approximate inclination angle of the introducing portionrelative to the insertion direction is greater than the approximateinclination angle of the guiding portion relative to the insertiondirection.
 10. The side release buckle of claim 8, wherein theintroducing portion extends to the insertion opening.
 11. The siderelease buckle of claim 8, wherein an approximate inclination angle ofthe introducing portion relative to the insertion direction is differentfrom the approximate inclination angle of the guiding portion relativeto the insertion direction.
 12. The side release buckle of claim 6,wherein the guide surfaces each comprise a step formed in the innersurface of the housing space.
 13. The side release buckle of claim 6,wherein at least one of the squeezing portion and the guiding portiondefine a straight surface.
 14. The side release buckle of claim 6,wherein at least one of the squeezing portion and the guiding portiondefine a curved surface.
 15. The side release buckle of claim 6, whereinthe socket engaging portion of each leg defines a raised tip proximatean end of the leg, the raised tip projecting in a top-bottom direction.16. The side release buckle of claim 6, wherein the socket furthercomprises a first cutout area between a top surface of the socket andthe socket belt attachment and a second cutout area between a bottomsurface of the socket and the socket belt attachment, wherein the secondcutout area is larger than the first cutout area.
 17. The side releasebuckle of claim 16, wherein the socket engaging portions of the plug areproximate a tip of each leg; and wherein the at least two plug engagingportions of the socket comprise four plug engaging portions configuredto engage the socket engaging portions of the plug when the socket andplug are engaged.
 18. The side release buckle of claim 17, wherein twoof the plug engaging portions of the socket are inset relative an edgeof the first cutout area and the other two of the plug engaging portionsof the socket are proximate an edge of the second cutout area.
 19. Aside release buckle comprising: (a) a plug, comprising: (i) a plug beltattachment and (ii) a pair of legs, each leg including at least onesocket engaging portion; (b) a socket, comprising: (i) a socket beltattachment, (ii) a housing space configured to receive at least portionsof the pair of legs, (iii) at least two plug engaging portions definingsurfaces that are approximately perpendicular to an insertion directionof the plug into the socket, the engaging portions configured to engagethe at least one socket engaging portion of each leg when the plug isinserted into the socket along the insertion direction, and (iv) atleast a pair of guide surfaces extending along an inner surface of thehousing space and configured to interact with the socket engagingportions of the plug in a sliding fashion, wherein the guide surfaceseach include at least a guiding portion and a squeezing portion, thesqueezing portion located between the guiding portion and one of theplug engaging portions, wherein an approximate inclination angle of thesqueezing portion relative to the insertion direction is greater than anapproximate inclination angle of the guiding portion relative to theinsertion direction, and wherein a length of the guiding portion alongthe insertion direction is longer than a length of the squeezing portionalong the insertion direction.
 20. The side release buckle of claim 19,wherein the guiding portions of the pair of guide surfaces arenon-parallel.
 21. The side release buckle of claim 19, wherein theguiding portion is continuous with the squeezing portion of each guidesurface.
 22. The side release buckle of claim 19, wherein the socketfurther comprises a central outer surface positioned such that it islocated between the pair of legs when the plug is inserted into thesocket, wherein the central outer surface is recessed relative to atleast two outer peripheral surfaces of the socket proximate the centralouter surface.
 23. The side release buckle of claim 19, wherein thesocket further comprises a first cutout area between a top surface ofthe socket and the socket belt attachment and a second cutout areabetween a bottom surface of the socket and the socket belt attachment,wherein the second cutout area is larger than the first cutout area. 24.The side release buckle of claim 23, wherein the socket engagingportions of the plug are proximate a tip of each leg; and wherein the atleast two plug engaging portions of the socket comprise four plugengaging portions configured to engage the socket engaging portions ofthe plug when the socket and plug are engaged.
 25. The side releasebuckle of claim 24, wherein two of the plug engaging portions of thesocket are inset relative an edge of the first cutout area and the othertwo of the plug engaging portions of the socket are proximate an edge ofthe second cutout area.